According tomedia CNET, the Earth’s magnetic field has been a bit abnormal. A region over the South Atlantic from Africa to South America has experienced a strong decline since the 1950s, and anomalies seem ready to fall in two over the past five years. This has caused some concern among scientists because the magnetic field is like the Earth’s umbrella, protecting us from charged particles in space. It is thought that this anomaly could signal a reversal of our magnetic poles, which could damage power and navigation systems.
But a new study published Monday in the Proceedings of the National Academy of Sciences suggests that the anomaly may not be as unusual as it seems — in fact, it may occur regularly. Researchers from the University of Liverpool analysed rocks that erupted between 8 and 11 million years ago. Previous research has shown that this anomaly has been around for a thousand years or more, but the Liverpool team believes this goes further.
The team collected 225 samples from 46 different locations on St. Helena, an island in the South Atlantic that was located below the magnetic field and was home to two volcanoes that formed at the same time. Volcanic rock provides a window through time, allowing researchers to understand what the magnetic field looked like hundreds of years ago. When lava flows cool and harden, the minerals “trapped” inside record the strength and direction of the magnetic field at that time.
“Our study is the first long-term analysis of the magnetic field in this area, dating back millions of years,” said Yael Engbers, a doctoral student at the University of Liverpool. “It suggests that the South Atlantic anomaly is a recurring feature and may not be a sign of an imminent reversal.”
The researchers speculate that their findings also support the view that the interaction of the Earth’s innermost layers may well be the cause of the strange decline in the field. Scientists have discovered a huge rocky area under the unusual Earth’s mantle, known as the African Low Shear Wave Speed Zone (ALLSVP). Changes in the geochemical composition of this ALLSVP may be the cause of the decline.
“This brings us closer to directly linking the behavior of the geomagnetic field to the characteristics of the Earth’s interior, ” Engbers said.
Understanding this anomaly is of great significance for future research and satellite security. A spacecraft called Hitomi, the Japanese space agency, is thought to have been affected by the anomaly. Because of the weak magnetic field, spacecraft passing through the region are more vulnerable to radiation from space. In 2016, Hitomi ran into communication problems as it passed over SAA. Shortly after, it accident and split into multiple fragments.